package com.itbac.config;

import com.alibaba.csp.sentinel.adapter.gateway.common.SentinelGatewayConstants;
import com.alibaba.csp.sentinel.adapter.gateway.common.api.ApiDefinition;
import com.alibaba.csp.sentinel.adapter.gateway.common.api.ApiPathPredicateItem;
import com.alibaba.csp.sentinel.adapter.gateway.common.api.ApiPredicateItem;
import com.alibaba.csp.sentinel.adapter.gateway.common.api.GatewayApiDefinitionManager;
import com.alibaba.csp.sentinel.adapter.gateway.common.rule.GatewayFlowRule;
import com.alibaba.csp.sentinel.adapter.gateway.common.rule.GatewayRuleManager;
import com.alibaba.csp.sentinel.adapter.gateway.sc.SentinelGatewayFilter;
import com.alibaba.csp.sentinel.adapter.gateway.sc.callback.BlockRequestHandler;
import com.alibaba.csp.sentinel.adapter.gateway.sc.callback.GatewayCallbackManager;
import com.alibaba.csp.sentinel.adapter.gateway.sc.exception.SentinelGatewayBlockExceptionHandler;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.codec.ServerCodecConfigurer;
import org.springframework.web.reactive.function.BodyInserters;
import org.springframework.web.reactive.function.server.ServerResponse;
import org.springframework.web.reactive.result.view.ViewResolver;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

import javax.annotation.PostConstruct;
import java.util.*;

/**
 * 网关配置,整合sentinel限流
 */

@Configuration
public class GatewayConfiguration {
    private final List<ViewResolver> viewResolvers;

    private final ServerCodecConfigurer serverCodecConfigurer;

    public GatewayConfiguration(ObjectProvider<List<ViewResolver>> viewResolversProvider, ServerCodecConfigurer serverCodecConfigurer) {
        this.viewResolvers = viewResolversProvider.getIfAvailable(Collections::emptyList);
        this.serverCodecConfigurer = serverCodecConfigurer;
    }
    //全局过滤器
    //Gateway整合sentinel过滤器
    //最小值,优先级高。
    @Bean
    @Order(Ordered.HIGHEST_PRECEDENCE)
    public GlobalFilter sentinelGatewayFilter() {
        return new SentinelGatewayFilter();
    }
    //配置初始化的限流参数
    @PostConstruct
    public void initGatewayRules(){
        Set<GatewayFlowRule> rules = new HashSet<>();
        //TODO 灵活配置，网关限流规则
        //1.路由维度，网关限流
        rules.add(
                //资源名称，对应路由id
                new GatewayFlowRule("product_route")
                        //限流阀值
                        .setCount(1)
                        //统计时间窗口，单位是秒，默认是1秒
                        .setIntervalSec(1)
        );
        /**
         * 2.API分组的维度，网关限流
         *  @see GatewayConfiguration#initCustomizedApis()
         */
        rules.add(new GatewayFlowRule("product_api1").setCount(1));
        rules.add(new GatewayFlowRule("product_api2").setCount(1));

        GatewayRuleManager.loadRules(rules);
    }
    //限流异常处理器
    @Bean
    @Order(Ordered.HIGHEST_PRECEDENCE)
    public SentinelGatewayBlockExceptionHandler sentinelGatewayBlockExceptionHandler(){
        return new SentinelGatewayBlockExceptionHandler(viewResolvers, serverCodecConfigurer);
    }
    //自定义限流异常页面
    @PostConstruct
    public void initBlockHandlers(){
        BlockRequestHandler blockRequestHandler = new BlockRequestHandler() {
            @Override
            public Mono<ServerResponse> handleRequest(ServerWebExchange serverWebExchange, Throwable throwable) {
                Map<String, Object> map = new HashMap<>();
                //com.itbac.config.sentinel.ExceptionHandlerPage
                map.put("code", -1);
                map.put("message", "接口被gateway整合sentinel是限流了");
                return ServerResponse.status(HttpStatus.OK)
                        .contentType(MediaType.APPLICATION_JSON_UTF8)
                        .body(BodyInserters.fromObject(map));
            }
        };
        GatewayCallbackManager.setBlockHandler(blockRequestHandler);
    }

    //自定义API分组
    @PostConstruct
    private void initCustomizedApis() {
        Set<ApiDefinition> definitions = new HashSet<>();
        ApiDefinition api1 = new ApiDefinition("product_api1")
                .setPredicateItems(
                        new HashSet<ApiPredicateItem>() {{
                            //以固定路径开头，后面模糊匹配
                            add(new ApiPathPredicateItem().setPattern("/product-serv/product/api1/**")
                                    .setMatchStrategy(SentinelGatewayConstants.URL_MATCH_STRATEGY_PREFIX)
                            );
                        }}
                );
        ApiDefinition api2 = new ApiDefinition("product_api2")
                .setPredicateItems(
                        new HashSet<ApiPredicateItem>() {{
                            //url路径完全匹配
                            add(new ApiPathPredicateItem().setPattern("/product-serv/product/api2/demo1")
                            );
                        }}
                );
        definitions.add(api1);
        definitions.add(api2);
        //加载分组策略
        GatewayApiDefinitionManager.loadApiDefinitions(definitions);
    }


}
